The past practice of employing personnel to travel a route to visually read utility meters has in some instances been discontinued, in favor of techniques which allow for remotely reading the usage data of different types of utility services. For example, one common practice for obtaining the water usage of a residential or business is to employ a special water meter device which stores the number of gallons used, and to connect such device to a telephone line. In this manner, the telephone line can be utilized by the water utility to remotely access the storage device to determine the amount of water used.
Another example of the capability of remotely accessing utility meters involves relatively new electrical utility usage meters. Here, the extent of the use of the electricity, generally in kilowatt hours, is stored in a memory, or similar read/write device. Each such electrical meter has a unique identity so that when interrogated from a remote location, the usage data of a particular meter can be obtained. Further, the telemetry of signals between the electric meter and a remote accounting office is carried out by way of modulation of the AC power line. This technique as the advantage that no additional telephone line is required and thus the transmission medium incurs no additional cost, and the telemetry of utility usage signals does not hamper or interfere with the general distribution of AC power. Moreover, since the utility usage signals are superimposed on the AC line voltage, the utility meters can be remotely accessed at every location where there is a distribution of AC power.
Because the electric and water utilities are generally independent entities, the development of the two different types of remote meter reading techniques has developed. As a result, it is believed that without the availability of the present invention, electric utilities would remotely access the electric meters via the AC power lines to obtain readings, while the water utilities would remotely access the water meters utilizing the telephone system.
It can be appreciated that in employing either of the above-mentioned techniques, an important consideration is the reliability of the systems to properly register the correct usage of the utility. This problem can be significant in the utility field, where unless otherwise accounted for, erroneous usage indications could be registered in the meter. If an erroneous excessive accumulation is registered during a power outage or lightning strike to the lines, or other intermittent interruptions occur, then the customer is overcharged. On the other hand, if the registration of usage data in the storage memory is insufficient, the utility company is deprived of revenue.
It can be seen from the foregoing that a need exists for an improved technique for providing a central meter storage area such that the usage data of each type of utility of a residence or business can be stored in a single storage medium and made available for remote accessing. A more particular need exists for an interface adapted for use with an electric utility meter which enables the input thereto of usage data of other types of utilities. A further need exists for a technique for accessing and remotely reading electrical, water and/or other usage data from a single data base, and transmitting such information over the AC power line.